This invention relates to apparatus for treating waste products and in particular, to a waste treatment tank construction adaptable to a variety of uses.
Aeration process treatment tanks are well known in the art, and their basic operational processes are given, for example, in U.S. patents to Weiss, U.S. Pat. No. 3,161,590, Kibbee, U.S. Pat. No. 3,195,727, Ziegler, U.S. Pat. No. 3,744,637, and references cited therein. In general, waste treatment tanks based on an aeration process have two tank sections, commonly known in the art as an aeration section and a clarification section. Raw sewage is introduced into the aeration tank section, where it is mixed with air. The air aids in the multiplication of bacteria which convert the raw sewage solution into a decomposed mixture. The decomposed mixture enters the clarification section, where the treated effluent leaves the tank as an unoffensive liquid.
Prior art waste treatment systems have either utilized a plurality of tank sections separated by elaborate baffle systems, or have utilized two tank sections and employed a vertical circulatory pattern in the aeration tank section, or some combination of both types. In a vertical circulatory pattern, flow in the aeration section is induced by suitable means so that the sewage mixture flows across the top liquid level of the tank, down the side of the tank, across the tank bottom, and upwardly along a suitable baffle for a clockwise vertical circulatory pattern, the tank being viewed in cross section. Of course, the flow pattern is reversed when a counterclockwise vertical circulatory pattern is employed. While these prior art devices work well for their intended purposes, I have developed a novel tank structure which utilizes a horizontal circulatory flow pattern, thereby simplifying tank construction and lowering product cost. In a horizontal circulatory flow pattern, the sewage mixture flows around the tank between at least two concentrically arranged circular walls, the tank being viewed in top plan. In addition, the means for generating the circulatory pattern in the aeration section of the tank includes a connector means employing a venturi principle both for drawing air into the aeration section, and for operating a solid skimmer means in the clarification tank section.